commit - 9b1d51628a0607649aa115d28b74ffe730fb9c78
commit + 7f8fc4ec0150a8db7769565c60168b34ce0bc907
blob - /dev/null
blob + f19f0a407da1cd971837ccc4b575836d81fd45b9 (mode 644)
--- /dev/null
+++ lib/pack.h
+
+/*
+ * Copyright (c) 2017 Stefan Sperling <stsp@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* See Documentation/technical/pack-format.txt in Git. */
+
+struct got_pack_obj_id {
+ u_int8_t sha1[SHA1_DIGEST_LENGTH];
+} __attribute__((__packed__));
+
+struct got_pack_idx_trailer {
+ u_int8_t pack_file_sha1[SHA1_DIGEST_LENGTH];
+ u_int8_t pack_idx_sha1[SHA1_DIGEST_LENGTH];
+} __attribute__((__packed__));
+
+/* Ignore pack index version 1 which is no longer written by Git. */
+#define GOT_PACKIDX_VERSION 2
+
+struct got_packidx_v2_hdr {
+ uint32_t magic; /* big endian */
+#define GOT_PACKIDX_V2_MAGIC 0xff744f63 /* "\377t0c" */
+ uint32_t version;
+
+ /*
+ * Each entry N in the fanout table contains the number of objects in
+ * the packfile whose SHA1 begins with a byte less than or equal to N.
+ * The last entry (index 255) contains the number of objects in the
+ * pack file whose first SHA1 byte is <= 0xff, and thus records the
+ * total number of objects in the pack file. All pointer variables
+ * below point to tables with a corresponding number of entries.
+ */
+ uint32_t fanout_table[0xff]; /* values are big endian */
+
+ /* Sorted SHA1 checksums for each object in the pack file. */
+ struct got_pack_obj_id *sorted_ids;
+
+ /* Offset into the pack file for each object. */
+ uint32_t *offsets; /* values are big endian */
+#define GOT_PACKIDX_OFFSET_VAL_MASK 0x7fffffff
+#define GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX 0x80000000
+
+ /* CRC32 of the packed representation of each object. */
+ uint32_t *crc32;
+
+ /* Large offsets table is empty for pack files < 2 GB. */
+ uint64_t *large_offsets; /* values are big endian */
+
+ struct got_pack_idx_trailer trailer;
+};
+
+struct got_packfile_hdr {
+ uint32_t signature;
+#define GOT_PACKFILE_SIGNATURE 0x4041434b /* 'P' 'A' 'C' 'K' */
+ uint32_t version; /* big endian */
+#define GOT_PACKFILE_VERSION 2
+ uint32_t nobjects; /* big endian */
+};
+
+struct got_packfile_obj_hdr {
+ /*
+ * The object size field uses a variable length encoding:
+ * size0...sizeN form a 4+7+7+...+7 bit integer, where size0 is the
+ * least significant part and sizeN is the most significant part.
+ * If the MSB of a size byte is set, an additional size byte follows.
+ * Of the 7 remaining bits of size0, the first 3 bits indicate the
+ * object's type, and the remaining 4 bits contribute to the size.
+ */
+ uint8_t *size; /* variable length */
+#define GOT_PACK_OBJ_SIZE_MORE 0x80
+#define GOT_PACK_OBJ_SIZE0_TYPE_MASK 0x70 /* See struct got_object->type */
+#define GOT_PACK_OBJ_SIZE0_VAL_MASK 0x0f
+#define GOT_PACK_OBJ_SIZEN_VAL_MASK 0x7f
+};
+
+/* If object is not a DELTA type. */
+struct got_packfile_object_data {
+ uint8_t *data; /* compressed */
+};
+
+/* If object is of type GOT_OBJ_TYPE_REF_DELTA. */
+struct got_packfile_object_data_ref_delta {
+ struct got_pack_obj_id id;
+ uint8_t *delta_data; /* compressed */
+};
+
+/* If object is of type GOT_OBJ_TYPE_OFFSET_DELTA. */
+struct got_packfile_object_data_offset_delta {
+ /*
+ * This offset is interpreted as a negative offset from
+ * the got_packfile_obj_hdr corresponding to this object.
+ * The size provided in the header specifies the amount
+ * of compressed delta data that follows.
+ *
+ * This field uses a variable length encoding of N bytes,
+ * where the MSB is always set except for the last byte.
+ * The value is encoded as a series of N 7 bit integers,
+ * which are concatenated, and if N > 1 the value 2^7 +
+ * 2^14 + ... + 2^(7 * (n-1)) is added to the result.
+ */
+ uint8_t *offset; /* variable length */
+};
+
+struct got_packfile_obj_data {
+ union {
+ struct got_packfile_object_data;
+ struct got_packfile_object_data_ref_delta;
+ struct got_packfile_object_data_offset_delta;
+ } __attribute__((__packed__));
+} __attribute__((__packed__));
